I think I would add courtesy. It implys a lot but the core of it is that you treat the other with respect and kindness.

I think many people will see any of the C's as being weak or making themself vunerable. To some extent that is true because it does require a certain level of a "C" that is not listed; Confidence;that the person you love actually finds you loveable and will not abuse your effort to be compassionate, communicate, compromise, and be committed to the relationship.